Chapter 9 SQ

9.8
How accurately do we need to read the value from Figure 9.5 a.

Fine Tuning

How accurate should our calculations be for the tuning constants?

	Within ± 0.10% of the exact value
	Within ± 1.0% of the exact value
	Within ± 10% of the exact value
	Within ± 100% of the exact value

9.9a
Diagnose the control performance in the following figure and recommend any needed changes to the feedback, PI controller tuning.

Fine Tuning

This is Question 9.9a; several diagnostic cases are given in parts a - d.

	The controller is well tuned, no tuning change required
	Increase the controller gain, Kc
	Decrease the controller gain, Kc
	Increase the controller Integral time, TI
	Decrease the controller Integral time, TI

9.9b
Diagnose the control performance in the following figure and recommend any needed changes to the feedback, PI controller tuning.

Fine Tuning

This is Question 9.9b; several diagnostic cases are given in parts a - d.

	The controller is well tuned, no tuning change required
	Increase the controller gain, Kc
	Decrease the controller gain, Kc
	Increase the controller integral time, TI
	Decrease the controller integral time, TI

9.9c
Diagnose the control performance in the following figure and recommend any needed changes to the feedback, PI controller tuning.

Fine Tuning

This is Question 9.9c; several diagnostic cases are given in parts a - d.

	The controller is well tuned, no tuning change required
	Increase the controller gain, Kc
	Decrease the controller gain, Kc
	Increase the controller integral time, TI
	Decrease the controller integral time, TI

9.9d
Diagnose the control performance in the following figure and recommend any needed changes to the feedback, PI controller tuning.

Fine Tuning

This is Question 9.9d; several diagnostic cases are given in parts a - d.

	The controller is well tuned, no tuning change required
	Increase the controller gain, Kc
	Decrease the controller gain, Kc
	Increase the controller integral time, TI
	Decrease the controller integral time, TI

9.10
Determine which of the following statements are true, and discuss.

Click on the statement(s) that you believe to be true.

	When the controlled variable behavior is good, we have attained good control performance.
	When tuning, we first evaluate the process reaction curve with the controller in operation.
	The "Lopez" tuning rules are best for non-self-regulatory processes.
	We use a set point change when fine tuning because it can be implemented whenever we want.

9.11
For the MIXING process in Figure 9.1, how do the key process model parameters change as the production rate (F_B) decreases? (K_P= gain, t = time constant, q = dead time)

Why are we interested? When F_B changes, we want to know if the controller tuning constants should be modified.

	all increase
	all decrease
	K_P increases, q and t decrease
	K_P decreases, q and t increase

9.12
As the fraction dead time, q/(q+t), increases, the PID tuning becomes more aggressive to overcome the process delay. (K_P= gain, t = time constant, q = dead time)

Fine Tuning

Consider the situation in which the dead time plus time constant remain constant. This could occur for the mixing process below if the pipe were lengthened and the tank volume were decreased simultaneously.